RESUMO
Transverse cracking is a serious problem for semi-rigid base asphalt pavement. The shrinkage of the base course and the surface course, as well as reflective cracks, are key factors for transverse cracking in asphalt pavement. Crack spacing can directly reflect the degree of transverse cracking in pavements. Therefore, this study aims to calculate the transverse crack spacing and discuss its affecting factors. To this end, a calculation model of transverse crack spacing for the semi-rigid base asphalt pavement was first established. Then, the transverse crack spacings of different composite structures were calculated, and the influences of the shrinkage coefficient, the structural layer thickness, and the pavement tensile strength on transverse crack spacing were expounded. Finally, the transverse crack spacing of the pavement after the appearance of the reflective was calculated. The results show that the lower lime and fly ash content and skeleton gap gradation can be adopted during the design of the base course. Meanwhile, the lower lime and fly ash content in the macadam base, the skeleton gap gradation and asphalt concrete with a larger particle size in the surface layer can be used during the design of surface layer. In addition, the transverse crack spacing of the semi-rigid base asphalt pavement could be increased by reducing the shrinkage coefficient, increasing the thicknesses of the surface course and the base course, and improving the tensile strength of the pavement. After the appearance of reflective cracks, the transverse crack spacing of the surface layer ranged between 32.8 m and 66.5 m. 15fp-AC25, 15fp-AC20, 15df-AC25, and 17fp-AC25 were found to be the best semi-rigid base asphalt pavement structures to reduce transverse cracking. Finally, transverse cracking in pavement composite structures under different bonding conditions needs to be analyzed in the follow-up work.
RESUMO
BACKGROUND: The BES1 gene family, an important class of plant-specific transcription factors, play key roles in the BR signal pathway in plants, regulating various development processes. Until now, there has been no comprehensive analysis of the BES1 gene family in Brassica napus, and a cross-genome exploration of their origin, copy number changes, and functional innovation in plants was also not available. RESULTS: We identified 28 BES1 genes in B. napus from its two subgenomes (AA and CC). We found that 71.43% of them were duplicated in the tetraploidization, and their gene expression showed a prominent subgenome bias in the roots. Additionally, we identified 104 BES1 genes in another 18 representative angiosperms and performed a comparative analysis with B. napus, including evolutionary trajectory, gene duplication, positive selection, and expression pattern. Exploiting the available genome datasets, we performed a large-scale analysis across plants and algae suggested that the BES1 gene family could have originated from group F, expanding to form other groups (A to E) by duplicating or alternatively deleting some domains. We detected an additional domain containing M4 to M8 in exclusively groups F1 and F2. We found evidence that whole-genome duplication (WGD) contributed the most to the expansion of this gene family among examined dicots, while dispersed duplication contributed the most to expansion in certain monocots. Moreover, we inferred that positive selection might have occurred on major phylogenetic nodes during the evolution of plants. CONCLUSIONS: Grossly, a cross-genome comparative analysis of the BES1 genes in B. napus and other species sheds light on understanding its copy number expansion, natural selection, and functional innovation.
